使用python在一行中用动态值替换字符串

Question

我有一个文件，基本上它是 json 中的响应，但我可以将它视为文件中的字符串行。我需要用动态值替换键的某些值，例如取值，进行一些计算并替换为该计算值。

例如（日期更改为 +1）：

"dateFrom":"Jun 24, 2018 10:00:34 AM" 到 "dateFrom":"Jun 25, 2018 10:00:34 AM"

示例字符串是：

line = {"Num":"ML3","dateFrom":"Jun 24, 2018 10:00:34 AM","Val":"mean to","dateTo":"Jun 27, 2018 10:00:34 AM","requestInfo":{"requestIdentifier":"7cecc67d"}}

我试图通过使用正则表达式来解决这个问题，如下所示（“TEST”）是虚拟值，但我必须采用 date 并替换为 date+1：

lt = re.sub(r'dateFrom|dateTo.*":(.*AM|PM)(.*)",',"TEST", line, re.IGNORECASE)

最终没有得到正确的输出。

预期：

line = {"Num":"ML3","dateFrom":"Jun 25, 2018 10:00:34 AM","Val":"mean to","dateTo":"Jun 28, 2018 10:00:34 AM","requestInfo":{"requestIdentifier":"7cecc67d"}}

非常感谢任何帮助。

提前致谢。

样本数据是： {"lAttributes":[{"Identifier":{"newIdentifier":{"DDline":"BM","guideIdDate":"Jun 25, 2018 12:00:00 AM","guideNo":"MM","suffix":"A"},"origin":"FRY","destination":"DZ"},"guideOwner":"VX","guideRegistration":"DD","guideType":"44","bestDepartureStatus":"S","bestArrivalTime":"Jun 25, 2018 6:00:00 AM","bestArrivalStatus":"S","bestDepartureTime":"Jun 25, 2018 5:00:00 AM","compartments":[{"code":"DD","guideCapacity":8,"guideBooked":0,"guideForecast":0},{"code":"DD","guideCapacity":10,"guideBooked":0,"guideForecast":0},{"code":"DD","guideCapacity":32,"guideBooked":0,"guideForecast":0},{"code":"DD","guideCapacity":24,"guideBooked":0,"guideForecast":0}]}]}

Answer 1

您可以像这样为字典键分配一个值：

from datetime import datetime, timedelta

line = {"Num":"ML3","dateFrom":"Jun 24, 2018 10:00:34 AM","Val":"mean to","dateTo":"Jun 27, 2018 10:00:34 AM","requestInfo":{"requestIdentifier":"7cecc67d"}}

# Adds 1 day to dateFrom
new_date = datetime.strptime(line["dateFrom"], '%b %d, %Y %I:%M:%S %p') + timedelta(days=1)

# Formats new date as a string and assigns it to dictionary key
line["dateFrom"] = datetime.strftime(new_date, '%b %d, %Y %I:%M:%S %p')

print(line)
>>>{'Num': 'ML3', 'dateFrom': 'Jun 25, 2018 10:00:34 AM', 'Val': 'mean to', 'dateTo': 'Jun 27, 2018 10:00:34 AM', 'requestInfo': {'requestIdentifier': '7cecc67d'}}

---

如果您需要将 json 字符串表示形式转换为字典（这在您的问题中有点不清楚），您可以使用 json 库：

import json

line = '{"Num":"ML3","dateFrom":"Jun 24, 2018 10:00:34 AM","Val":"mean to","dateTo":"Jun 27, 2018 10:00:34 AM","requestInfo":{"requestIdentifier":"7cecc67d"}}'

line = json.loads(line)